The SpringLinear property of the FixedJoint class specifies the linear spring characteristics of the joint. It determines how springy and tight the joint will be in its linear movement, affecting how it responds to forces and how it returns to its original position after being displaced.

To use the SpringLinear property, you need to have an instance of the FixedJoint class. You can then get or set the SpringLinear property to adjust the linear spring behavior of the joint.

Example usage:

FixedJoint myJoint = new FixedJoint();
PhysicsSpring springSettings = new PhysicsSpring();
springSettings.Stiffness = 100.0f;
springSettings.Damping = 0.5f;

myJoint.SpringLinear = springSettings;

In this example, a new FixedJoint is created, and its SpringLinear property is set to a PhysicsSpring object with specified stiffness and damping values.